Download (AIS). - Whitworths Marine & Leisure

IC-M505 VHF MARINE with built in
Automatic Identification System
(AIS).
I.
Presenting AIS
A.
B.
C.
D.
E.
II.
Introduction ...............................................................................................................
Ships under an obligation to transmit in AIS .........................................................
Description of the AIS system .................................................................................
Dynamic information ................................................................................................
Static information......................................................................................................
ICOM AIS
A.
B.
C.
The Problem issue ....................................................................................................
Intergrated Solution ..................................................................................................
Description ................................................................................................................
III. Using AIS
A.
B.
C.
D.
E.
Principle for using an ICOM VHF radio AIS module...............................................
Activation of AIS .......................................................................................................
Activation of scanning on the IC-M505 ...................................................................
Explanation of basic operation ................................................................................
Advanced operation (*).............................................................................................
I. Presenting AIS
A. Introduction
Designed as a navigation aid in busy waters. The Automatic
Identification System (AIS) was originally created by the Swede, Häkan
Lans.
B. Ships under an obligation to transmit in AIS
The IMO (International Maritime Organisation) was responsable for
making AIS compulsory for vessels under the SOLAS convention
(Safety of Life at Sea).
Vessels of 300 tonnes and over making international voyages must be
equipped with AIS, as well as cargo vessels of 500 tonnes and over not
intended for international voyages.
Vessels meeting the above criteria, built after 1 July 2002, must be
equipped with an approved AIS system. All other ships should have
been equipped by July 1st 2008.
C. Description of the AIS system
The role of AIS signals is to transmit and receive nautical information
such as speed, course and changes in course. Misunderstandings
between vessels are thus avoided and VHF channels less overloaded.
While radar provides basic information on the obstacles of a course, the
AIS provides additional data on the navigation of nearby boats (if
equipped with AIS transceivers). The AIS provides very accurate data
such as the speed and actual course of boats, as well as other data such
as their identification, size and sometimes their destination.
The AIS is based on digital radio communications where various
transceivers share transmission time.
The system is theoretically limited to 75 boats: however, when a large
number of boats are sailing in the same area, the AIS system
automatically reduces it’s receive radius to give greater importance to
the strongest/nearest signals retrieved.
To avoid risks linked to a transmission channel breakdown, the AIS
system functions in parallel on two frequencies in a frequency band
dedicated to maritime traffic. These frequencies are set by default to
(maritime channel 87B) and (maritime channel 88B).
The data transmitted is time-staggered on the two channels in order to
reduce refreshment time.
This information is classified in two categories: dynamic and static
types of information.
D. Dynamic information
This data is vital since it is relative to the "real time" movement of the
vessel.
The dynamic information sent by AIS signals is as follows:
MMSI :
ROT (Rate Of Turn):
Navigation status:
under sail
Latitude:
resolution
Longitude::
resolution
SOG (Speed Over Ground)
1/10ths of a knot
COG (Course Over Ground):
resolution
True Heading (Gyro Compass):
UTC Time for Creation of a Report:
seconds
Vessel identifier
Rotation speed
In port, manoeuvring,
1/10,000th minute
1/10,000th minute
Actual speed in
1/10,000th minute
Course in degrees
Hours, minutes and
(The refreshment time for this information may range from a few minutes to
two seconds, depending on the speed and manoeuvre being undertaken by the
vessel).
E. Static information
Every six minutes, additional static information is sent relative to the
vessel and its current journey; for example, the name of the vessel, the
onboard GPS position, the destination port, etc.
II. ICOM AIS
A. Problem issue
At sea, it soon becomes apparent that, due to their size &
maneuverability, Solas ships represent a definite risk for small,
craft. Unfortunately little consideration is afforded to small craft,
by these seagoing giants. The AIS system allows Mariners to monitor for
possible collisions (Some Chart Plotters allow for proximity alarms).
Additionally as the MMSI or (DSC number) is available (Via the AIS
system) this allows for the selective calling of vessels, especially useful
in emergency situations.
B. Intergrated Solution
On small craft, the need to have an on board receiver that decodes AIS
Data soon became essential to keep skippers advised of potential risks
of collision.
To be efficient, the receiver must be of good quality with the position of
the antenna as high & unobstructed as possible. These constraints are
not very compatible with boats where the numerous aerials and
equipment soon becomes a problem. For many sailing craft, a second
coaxial cable in the mast is not an option. This is why Icom engineers
sought to integrate the AIS decoder into a VHF radio, the aim being to
take advantage of both the performance linked to the excellence of Icom
receivers and easy installation for the user. No external casing or
additional antenna are then required and craft benefit from the maximum
range that a masthead antenna can give.
C. Description
The AIS signal is serialised with the ASN signal so that it can be used by
an external system (software, plotter, etc.) on one serial port.
With this generation, the GPS position can be added to the AIS and ASN
phrases, still on one 4800 Baud port. There are a number of compatible
onboard mapping systems (Shipplotter, Sw&N, Maxsea, Furuno, etc.).
III. Using AIS
A. Principle for using an ICOM VHF radio with a AIS module
IMPORTANT: The following information is a supplement to the IC-M505
instruction manual. Please ensure you have read the IC-M505 manual
before reading the following information.
Once the VHF radio has been fitted with the AIS module, VHF reception
simply needs to be activated manually on one or other of the AIS
channels or by simultaneously scanning both AIS channels.
(Programming will have been carried out beforehand to add the two AIS
frequencies to the IC-M505 AIS, they are programmed as P1 & P2). The
NMEA output must also be connected to the correctly configured final
equipment.
The IC-M505 AIS uses standard 9 pin D-Subminiature connectors for
NMEA input & output.
NMEA OUT
Pin 2 NMEA out
Pin 5 GND
NMEA IN
Pin 2 NMEA
Pin 5 GND
B. Activation of AIS
The two AIS 1 (P1) and AIS 2 (P2) channels are marked by default with a
TAG (see the VHF radio user manual to understand the role of the tag in
scanning), which means they will be scanned when the scan function is
activated. This is the easiest method of AIS implementation. You will
thus continue to listen in to your favourite channels while AIS
information is being regularly transmitted to the NMEA output and your
chart plotter or PC.
(The IC-M505 allows all Tagged channels to be cleared (Untagged)
simultaneously please see the instructions. P13).
C. Activation of scanning on the IC-M505 AIS
Figure 7: Front panel of the IC-M505 AIS
1) Briefly press the Scan key, identified by the number 10 on the above
view. Note: Channel 70 (DSC) is typically always scanned. The Radio
can be set up for dual-watch or tri-watch scanning to listen in to channel
16, a preferred channel & a AIS Channel(s). (See the instructions for
further information on dual-watch & tri-watch. P14).
D. Explanation of basic operation
The VHF radio, when in scanning mode will scan all the tagged
channels, then will stop when it encounters a busy channel and then
start scanning again when the channel is free.
With each passage on the AIS channels, data will be transmitted to the
navigation equipment to enable AIS targets to be displayed.
IMPORTANT: An audible sound is emitted each time AIS data is
received, this is normal.
This is the easiest method of use and it is sufficient to enable AIS
monitoring in the majority of cases. During VHF transmission or in
active receive mode (audio open) on other channels, AIS data is not
updated but this will occur when scanning next restarts.
E. Advanced operation (*)
(*) IMPORTANT: Advanced operation is an added safety measure
permitted by the potential of this equipment; it is not necessary to use it
during normal operation.
In particular conditions (no visibility, very dense traffic, imminent
danger of collision, etc.), if the skipper considers it pertinent for his
safety not to scan any other channel and only use AIS channel
reception, he has two options to obtain maximum information
refreshment:
1°) Stop scanning and only monitor one or other of the AIS channels,
chosen manually with the channel selection button. (Channels P1 or P2).
2) Scan only the two AIS channels by eliminating the tags of all other
channels. (The IC-M505 allows all Tagged channels to be cleared
(Untagged) simultaneously please see the instructions. P13).
IMPORTANT: The use of a navigation aid does not release the skipper
from the necessary vigilance in respect of the safety of equipment and
people.